Image coding method based on partial entry point-associated information in video or image coding system

ABSTRACT

According to the document of the present document, information/parameters associated with an entry point can be signaled on the basis of a WPP-associated entry point offset-present flag and a tile-associated entry point offset-present flag, and the effect of increasing coding efficiency, which is the primary purpose of parallel processing in encoding/decoding, can be derived therefrom.

BACKGROUND Field of the Document

The present document relates to video/image coding technology, and moreparticularly, to an image coding method based on partial entry pointassociated information in a video or image coding system.

Related Art

Recently, the demand for high resolution, high quality image/video suchas 4K, 8K or more Ultra High Definition (UHD) image/video is increasingin various fields. As the image/video resolution or quality becomeshigher, relatively more amount of information or bits are transmittedthan for conventional image/video data. Therefore, if image/video dataare transmitted via a medium such as an existing wired/wirelessbroadband line or stored in a legacy storage medium, costs fortransmission and storage are readily increased.

Moreover, interests and demand are growing for virtual reality (VR) andartificial reality (AR) contents, and immersive media such as hologram;and broadcasting of images/videos exhibiting image/video characteristicsdifferent from those of an actual image/video, such as gameimages/videos, are also growing.

Therefore, a highly efficient image/video compression technique isrequired to effectively compress and transmit, store, or play highresolution, high quality images/videos showing various characteristicsas described above.

SUMMARY

According to an embodiment of the present document, a method and anapparatus which increase image coding efficiency are provided.

According to an embodiment of the present document, a method and anapparatus which efficiently perform coding through WPP and/or tiletechnology are provided.

According to an embodiment of the present document, a method and anapparatus for signaling entry point related information are provided.

According to an embodiment of the present document, a method and anapparatus for signaling an entry point offset present flag related towhether to signal entry point offsets by dividing the entry point offsetpresent flag into an entry point offset present flag for WPP and a tileentry point offset present flag.

According to an embodiment of the present document, a video/imagedecoding method performed by a decoding apparatus is provided.

According to an embodiment of the present document, a decoding apparatusfor performing video/image decoding is provided.

According to an embodiment of the present document, a video/imageencoding method performed by an encoding apparatus is provided.

According to an embodiment of the present document, an encodingapparatus for performing video/image encoding is provided.

According to an embodiment of the present document, a computer-readabledigital storage medium storing encoded video/image information generatedaccording to the video/image encoding method disclosed in at least oneof the embodiments of the present document is provided.

According to an embodiment of the present document, a computer-readabledigital storage medium storing encoded information or encodedvideo/image information causing a decoding apparatus to perform thevideo/image decoding method disclosed in at least one of the embodimentsof the present document is provided.

According to an embodiment of the present document, it is possible toincrease overall image/video compression efficiency.

According to an embodiment of the present document, it is possible toefficiently perform coding through WPP or tile technology.

According to an embodiment of the present document, it is possible toefficiently signal entry point related information.

According to an embodiment of the present document, it is possible tosignal an entry point offset present flag related to whether to signalentry point offsets by dividing the entry point offset present flag intoan entry point offset present flag for WPP and a tile entry point offsetpresent flag.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically represents an example of a video/image codingsystem to which embodiments of the present document may be applied.

FIG. 2 is a diagram schematically describing a configuration of avideo/image encoding apparatus to which embodiments of the presentdocument may be applied.

FIG. 3 is a diagram schematically describing a configuration of avideo/image decoding apparatus to which embodiments of the presentdocument may be applied.

FIG. 4 exemplarily shows a hierarchical structure for a codedimage/video.

FIGS. 5 to 7 illustrate one embodiment in which a picture is partitionedinto slices and tiles.

FIG. 8 exemplarily shows initialization of a CABAC context model forWPP.

FIGS. 9 and 10 illustrate an example of a video/image encoding methodand related components according to an embodiment(s) of the presentdocument.

FIGS. 11 and 12 illustrate an example of a video/image decoding methodand related components according to an embodiment(s) of the presentdocument.

FIG. 13 illustrates an example of a contents streaming system to whichembodiments of the present document may be applied.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present document may be modified in various forms, and specificembodiments thereof will be described and illustrated in the drawings.However, the embodiments are not intended for limiting the document. Theterms used in the following description are used to merely describespecific embodiments, but are not intended to limit the document. Anexpression of a singular number includes an expression of the pluralnumber, so long as it is clearly read differently. The terms such as“include” and “have” are intended to indicate that features, numbers,steps, operations, elements, components, or combinations thereof used inthe following description exist and it should be thus understood thatthe possibility of existence or addition of one or more differentfeatures, numbers, steps, operations, elements, components, orcombinations thereof is not excluded.

In addition, each configuration of the drawings described in thisdocument is an independent illustration for explaining functions asfeatures that are different from each other, and does not mean that eachconfiguration is implemented by mutually different hardware or differentsoftware. For example, two or more of the configurations can be combinedto form one configuration, and one configuration can also be dividedinto multiple configurations. Without departing from the gist of thisdocument, embodiments in which configurations are combined and/orseparated are included in the scope of claims.

Hereinafter, examples of the present embodiment will be described indetail with reference to the accompanying drawings. In addition, likereference numerals are used to indicate like elements throughout thedrawings, and the same descriptions on the like elements will beomitted.

FIG. 1 illustrates an example of a video/image coding system to whichthe embodiments of the present document may be applied.

Referring to FIG. 1 , a video/image coding system may include a sourcedevice and a reception device. The source device may transmit encodedvideo/image information or data to the reception device through adigital storage medium or network in the form of a file or streaming.

The source device may include a video source, an encoding apparatus, anda transmitter. The receiving device may include a receiver, a decodingapparatus, and a renderer. The encoding apparatus may be called avideo/image encoding apparatus, and the decoding apparatus may be calleda video/image decoding apparatus. The transmitter may be included in theencoding apparatus. The receiver may be included in the decodingapparatus. The renderer may include a display, and the display may beconfigured as a separate device or an external component.

The video source may acquire video/image through a process of capturing,synthesizing, or generating the video/image. The video source mayinclude a video/image capture device and/or a video/image generatingdevice. The video/image capture device may include, for example, one ormore cameras, video/image archives including previously capturedvideo/images, and the like. The video/image generating device mayinclude, for example, computers, tablets and smartphones, and may(electronically) generate video/images. For example, a virtualvideo/image may be generated through a computer or the like. In thiscase, the video/image capturing process may be replaced by a process ofgenerating related data.

The encoding apparatus may encode input video/image. The encodingapparatus may perform a series of procedures such as prediction,transform, and quantization for compaction and coding efficiency. Theencoded data (encoded video/image information) may be output in the formof a bitstream.

The transmitter may transmit the encoded image/image information or dataoutput in the form of a bitstream to the receiver of the receivingdevice through a digital storage medium or a network in the form of afile or streaming. The digital storage medium may include variousstorage mediums such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, and thelike. The transmitter may include an element for generating a media filethrough a predetermined file format and may include an element fortransmission through a broadcast/communication network. The receiver mayreceive/extract the bitstream and transmit the received bitstream to thedecoding apparatus.

The decoding apparatus may decode the video/image by performing a seriesof procedures such as dequantization, inverse transform, and predictioncorresponding to the operation of the encoding apparatus.

The renderer may render the decoded video/image. The renderedvideo/image may be displayed through the display.

The present document relates to video/image coding. For example, amethod/embodiment disclosed in the present document may be applied to amethod disclosed in the versatile video coding (VVC) standard. Inaddition, a method/embodiment disclosed in the present document may beapplied to a method disclosed in the essential video coding (EVC)standard, the AOMedia Video 1 (AV1) standard, the 2nd generation ofaudio video coding standard (AVS2) or the next generation video/imagecoding standard (e.g., H.267, H.268, or the like).

The present document suggests various embodiments of video/image coding,and the above embodiments may also be performed in combination with eachother unless otherwise specified.

In the present document, a video may refer to a series of images overtime. A picture generally refers to the unit representing one image at aparticular time frame, and a slice/tile refers to the unit constitutinga part of the picture in terms of coding. A slice/tile may include oneor more coding tree units (CTUs). One picture may consist of one or moreslices/tiles. A tile is a rectangular region of CTUs within a particulartile column and a particular tile row in a picture. The tile column is arectangular region of CTUs having a height equal to the height of thepicture and a width specified by syntax elements in the pictureparameter set. The tile row is a rectangular region of CTUs having aheight specified by syntax elements in the picture parameter set and awidth equal to the width of the picture. A tile scan is a specificsequential ordering of CTUs partitioning a picture in which the CTUs areordered consecutively in CTU raster scan in a tile whereas tiles in apicture are ordered consecutively in a raster scan of the tiles of thepicture. A slice includes an integer number of complete tiles or aninteger number of consecutive complete CTU rows within a tile of apicture that may be exclusively contained in a single NAL unit

Meanwhile, one picture may be divided into two or more subpictures. Asubpicture may be a rectangular region of one or more slices within apicture.

A pixel or a pel may mean a smallest unit constituting one picture (orimage). Also, ‘sample’ may be used as a term corresponding to a pixel. Asample may generally represent a pixel or a value of a pixel, and mayrepresent only a pixel/pixel value of a luma component or only apixel/pixel value of a chroma component.

A unit may represent a basic unit of image processing. The unit mayinclude at least one of a specific region of the picture and informationrelated to the region. One unit may include one luma block and twochroma (ex. cb, cr) blocks. The unit may be used interchangeably withterms such as block or area in some cases. In a general case, an M×Nblock may include samples (or sample arrays) or a set (or array) oftransform coefficients of M columns and N rows.

In this document, “A or B” may mean “only A”, “only B” or “both A andB”. In other words, “A or B” in this document may be interpreted as “Aand/or B”. For example, in this document “A, B or C” means “only A”,“only B”, “only C”, or “any combination of A, B and C”.

A slash (/) or comma (,) used in this document may mean “and/or”. Forexample, “A/B” may mean “A and/or B”. Accordingly, “A/B” may mean “onlyA”, “only B”, or “both A and B”. For example, “A, B, C” may mean “A, B,or C”.

In this document, “at least one of A and B” may mean “only A”, “only B”or “both A and B”. Also, in this document, the expression “at least oneof A or B” or “at least one of A and/or B” means “at least one It can beinterpreted the same as “at least one of A and B”.

Also, in this document, “at least one of A, B and C” means “only A”,“only B”, “only C”, or “A, B and C” Any combination of A, B and C″.Also, “at least one of A, B or C” or “at least one of A, B and/or C”means may mean “at least one of A, B and C”.

Also, parentheses used in this document may mean “for example”.Specifically, when “prediction (intra prediction)” is indicated, “intraprediction” may be proposed as an example of “prediction”. In otherwords, “prediction” in this document is not limited to “intraprediction”, and “intra prediction” may be proposed as an example of“prediction”. Also, even when “prediction (i.e., intra prediction)” isindicated, “intra prediction” may be proposed as an example of“prediction”.

Technical features that are individually described in one drawing inthis document may be implemented individually or may be implemented atthe same time.

FIG. 2 is a diagram schematically illustrating a configuration of avideo/image encoding apparatus to which the embodiments of the presentdocument may be applied. Hereinafter, what is referred to as theencoding apparatus may include an image encoding apparatus and/or avideo encoding apparatus.

Referring to FIG. 2 , the encoding apparatus 200 may include and beconfigured with an image partitioner 210, a predictor 220, a residualprocessor 230, an entropy encoder 240, an adder 250, a filter 260, and amemory 270. The predictor 220 may include an inter predictor 221 and anintra predictor 222. The residual processor 230 may include atransformer 232, a quantizer 233, a dequantizer 234, and an inversetransformer 235. The residual processor 230 may further include asubtractor 231. The adder 250 may be called a reconstructor orreconstructed block generator. The image partitioner 210, the predictor220, the residual processor 230, the entropy encoder 240, the adder 250,and the filter 260, which have been described above, may be configuredby one or more hardware components (e.g., encoder chipsets orprocessors) according to an embodiment. In addition, the memory 270 mayinclude a decoded picture buffer (DPB), and may also be configured by adigital storage medium. The hardware component may further include thememory 270 as an internal/external component.

The image partitioner 210 may split an input image (or, picture, frame)input to the encoding apparatus 200 into one or more processing units.As an example, the processing unit may be called a coding unit (CU). Inthis case, the coding unit may be recursively split according to aQuad-tree binary-tree ternary-tree (QTBTTT) structure from a coding treeunit (CTU) or the largest coding unit (LCU). For example, one codingunit may be split into a plurality of coding units of a deeper depthbased on a quad-tree structure, a binary-tree structure, and/or aternary-tree structure. In this case, for example, the quad-treestructure is first applied and the binary-tree structure and/or theternary-tree structure may be later applied. Alternatively, thebinary-tree structure may also be first applied. A coding procedureaccording to the present document may be performed based on a finalcoding unit which is not split any more. In this case, based on codingefficiency according to image characteristics or the like, the maximumcoding unit may be directly used as the final coding unit, or asnecessary, the coding unit may be recursively split into coding units ofa deeper depth, such that a coding unit having an optimal size may beused as the final coding unit. Here, the coding procedure may include aprocedure such as prediction, transform, and reconstruction to bedescribed later. As another example, the processing unit may furtherinclude a prediction unit (PU) or a transform unit (TU). In this case,each of the prediction unit and the transform unit may be split orpartitioned from the aforementioned final coding unit. The predictionunit may be a unit of sample prediction, and the transform unit may be aunit for inducing a transform coefficient and/or a unit for inducing aresidual signal from the transform coefficient.

The unit may be interchangeably used with the term such as a block or anarea in some cases. Generally, an M×N block may represent samplescomposed of M columns and N rows or a group of transform coefficients.The sample may generally represent a pixel or a value of the pixel, andmay also represent only the pixel/pixel value of a luma component, andalso represent only the pixel/pixel value of a chroma component. Thesample may be used as the term corresponding to a pixel or a pelconfiguring one picture (or image).

The encoding apparatus 200 may generate a residual signal (residualblock, residual sample array) by subtracting a predicted signal(predicted block, prediction sample array) output from the interpredictor 221 or the intra predictor 222 from the input image signal(original block, original sample array), and the generated residualsignal is transmitted to the transformer 232. In this case, asillustrated, the unit for subtracting the predicted signal (predictedblock, prediction sample array) from the input image signal (originalblock, original sample array) within an encoder 200 may be called thesubtractor 231. The predictor may perform prediction for a block to beprocessed (hereinafter, referred to as a current block), and generate apredicted block including prediction samples of the current block. Thepredictor may determine whether intra prediction is applied or interprediction is applied in units of the current block or the CU. Thepredictor may generate various information about prediction, such asprediction mode information, to transfer the generated information tothe entropy encoder 240 as described later in the description of eachprediction mode. The information about prediction may be encoded by theentropy encoder 240 to be output in a form of the bitstream.

The intra predictor 222 may predict a current block with reference tosamples within a current picture. The referenced samples may be locatedneighboring to the current block, or may also be located away from thecurrent block according to the prediction mode. The prediction modes inthe intra prediction may include a plurality of non-directional modesand a plurality of directional modes. The non-directional mode mayinclude, for example, a DC mode or a planar mode. The directional modemay include, for example, 33 directional prediction modes or 65directional prediction modes according to the fine degree of theprediction direction. However, this is illustrative and the directionalprediction modes which are more or less than the above number may beused according to the setting. The intra predictor 222 may alsodetermine the prediction mode applied to the current block using theprediction mode applied to the neighboring block.

The inter predictor 221 may induce a predicted block of the currentblock based on a reference block (reference sample array) specified by amotion vector on a reference picture. At this time, in order to decreasethe amount of motion information transmitted in the inter predictionmode, the motion information may be predicted in units of a block, asub-block, or a sample based on the correlation of the motioninformation between the neighboring block and the current block. Themotion information may include a motion vector and a reference pictureindex. The motion information may further include inter predictiondirection (L0 prediction, L1 prediction, Bi prediction, or the like)information. In the case of the inter prediction, the neighboring blockmay include a spatial neighboring block existing within the currentpicture and a temporal neighboring block existing in the referencepicture. The reference picture including the reference block and thereference picture including the temporal neighboring block may also bethe same as each other, and may also be different from each other. Thetemporal neighboring block may be called the name such as a collocatedreference block, a collocated CU (colCU), or the like, and the referencepicture including the temporal neighboring block may also be called acollocated picture (colPic). For example, the inter predictor 221 mayconfigure a motion information candidate list based on the neighboringblocks, and generate information indicating what candidate is used toderive the motion vector and/or the reference picture index of thecurrent block. The inter prediction may be performed based on variousprediction modes, and for example, in the case of a skip mode and amerge mode, the inter predictor 221 may use the motion information ofthe neighboring block as the motion information of the current block. Inthe case of the skip mode, the residual signal may not be transmittedunlike the merge mode. A motion vector prediction (MVP) mode mayindicate the motion vector of the current block by using the motionvector of the neighboring block as a motion vector predictor, andsignaling a motion vector difference.

The predictor 200 may generate a predicted signal based on variousprediction methods to be described later. For example, the predictor maynot only apply the intra prediction or the inter prediction forpredicting one block, but also simultaneously apply the intra predictionand the inter prediction. This may be called a combined inter and intraprediction (CIIP). Further, the predictor may be based on an intra blockcopy (IBC) prediction mode, or a palette mode in order to performprediction on a block. The IBC prediction mode or palette mode may beused for content image/video coding of a game or the like, such asscreen content coding (SCC). The IBC basically performs prediction in acurrent picture, but it may be performed similarly to inter predictionin that it derives a reference block in a current picture. That is, theIBC may use at least one of inter prediction techniques described in thepresent document. The palette mode may be regarded as an example ofintra coding or intra prediction. When the palette mode is applied, asample value in a picture may be signaled based on information on apalette index and a palette table.

The predicted signal generated through the predictor (including theinter predictor 221 and/or the intra predictor 222) may be used togenerate a reconstructed signal or used to generate a residual signal.The transformer 232 may generate transform coefficients by applying thetransform technique to the residual signal. For example, the transformtechnique may include at least one of a discrete cosine transform (DCT),a discrete sine transform (DST), a graph-based transform (GBT), or aconditionally non-linear transform (CNT). Here, when the relationshipinformation between pixels is illustrated as a graph, the GBT means thetransform obtained from the graph. The CNT means the transform which isacquired based on a predicted signal generated by using all previouslyreconstructed pixels. In addition, the transform process may also beapplied to a pixel block having the same size of the square, and mayalso be applied to the block having a variable size rather than thesquare.

The quantizer 233 may quantize the transform coefficients to transmitthe quantized transform coefficients to the entropy encoder 240, and theentropy encoder 240 may encode the quantized signal (information aboutthe quantized transform coefficients) to the encoded quantized signal tothe bitstream. The information about the quantized transformcoefficients may be called residual information. The quantizer 233 mayrearrange the quantized transform coefficients having a block form in aone-dimensional vector form based on a coefficient scan order, and alsogenerate the information about the quantized transform coefficientsbased on the quantized transform coefficients of the one dimensionalvector form. The entropy encoder 240 may perform various encodingmethods, for example, such as an exponential Golomb coding, acontext-adaptive variable length coding (CAVLC), and a context-adaptivebinary arithmetic coding (CABAC). The entropy encoder 240 may alsoencode information (e.g., values of syntax elements and the like)necessary for reconstructing video/image other than the quantizedtransform coefficients together or separately. The encoded information(e.g., encoded video/image information) may be transmitted or stored inunits of network abstraction layer (NAL) unit in a form of thebitstream. The video/image information may further include informationabout various parameter sets such as an adaptation parameter set (APS),a picture parameter set (PPS), a sequence parameter set (SPS), or avideo parameter set (VPS). In addition, the video/image information mayfurther include general constraint information. The signaled/transmittedinformation and/or syntax elements to be described later in the presentdocument may be encoded through the aforementioned encoding procedureand thus included in the bitstream. The bitstream may be transmittedthrough a network, or stored in a digital storage medium. Here, thenetwork may include a broadcasting network and/or a communicationnetwork, or the like, and the digital storage medium may include variousstorage media such as USB, SD, CD, DVD, Blue-ray, HDD, and SSD. Atransmitter (not illustrated) for transmitting the signal output fromthe entropy encoder 240 and/or a storage (not illustrated) for storingthe signal may be configured as the internal/external elements of theencoding apparatus 200, or the transmitter may also be included in theentropy encoder 240.

The quantized transform coefficients output from the quantizer 233 maybe used to generate a predicted signal. For example, the dequantizer 234and the inverse transformer 235 apply dequantization and inversetransform to the quantized transform coefficients, such that theresidual signal (residual block or residual samples) may bereconstructed. The adder 250 adds the reconstructed residual signal tothe predicted signal output from the inter predictor 221 or the intrapredictor 222, such that the reconstructed signal (reconstructedpicture, reconstructed block, reconstructed sample array) may begenerated. As in the case where the skip mode is applied, if there is noresidual for the block to be processed, the predicted block may be usedas the reconstructed block. The adder 250 may be called a reconstructoror a reconstructed block generator. The generated reconstructed signalmay be used for the intra prediction of the next block to be processedwithin the current picture, and as described later, also used for theinter prediction of the next picture through filtering.

Meanwhile, a luma mapping with chroma scaling (LMCS) may also be appliedin a picture encoding and/or reconstruction process.

The filter 260 may apply filtering to the reconstructed signal, therebyimproving subjective/objective image qualities. For example, the filter260 may apply various filtering methods to the reconstructed picture togenerate a modified reconstructed picture, and store the modifiedreconstructed picture in the memory 270, specifically, the DPB of thememory 270. Various filtering methods may include, for example, adeblocking filtering, a sample adaptive offset, an adaptive loop filter,a bilateral filter, and the like. The filter 260 may generate variouskinds of filtering-related information to transfer the generatedinformation to the entropy encoder 240, as described later in thedescription of each filtering method. The filtering-related informationmay be encoded by the entropy encoder 240 to be output in a form of thebitstream.

The modified reconstructed picture transmitted to the memory 270 may beused as the reference picture in the inter predictor 221. If the interprediction is applied by the inter predictor, the encoding apparatus mayavoid the prediction mismatch between the encoding apparatus 200 and thedecoding apparatus, and also improve coding efficiency.

The DPB of the memory 270 may store the modified reconstructed pictureto be used as the reference picture in the inter predictor 221. Thememory 270 may store motion information of the block in which the motioninformation within the current picture is derived (or encoded) and/ormotion information of the blocks within the previously reconstructedpicture. The stored motion information may be transferred to the interpredictor 221 to be utilized as motion information of the spatialneighboring block or motion information of the temporal neighboringblock. The memory 270 may store the reconstructed samples of thereconstructed blocks within the current picture, and transfer thereconstructed samples to the intra predictor 222.

FIG. 3 is a diagram for schematically explaining a configuration of avideo/image decoding apparatus to which the embodiments of the presentdocument may be applied.

Hereinafter, what is referred to as the decoding apparatus may includean image decoding apparatus and/or a video decoding apparatus.

Referring to FIG. 3 , the decoding apparatus 300 may include andconfigured with an entropy decoder 310, a residual processor 320, apredictor 330, an adder 340, a filter 350, and a memory 360. Thepredictor 330 may include an inter predictor 331 and an intra predictor332. The residual processor 320 may include a dequantizer 321 and aninverse transformer 322. The entropy decoder 310, the residual processor320, the predictor 330, the adder 340, and the filter 350, which havebeen described above, may be configured by one or more hardwarecomponents (e.g., decoder chipsets or processors) according to anembodiment. Further, the memory 360 may include a decoded picture buffer(DPB), and may be configured by a digital storage medium. The hardwarecomponent may further include the memory 360 as an internal/externalcomponent.

When the bitstream including the video/image information is input, thedecoding apparatus 300 may reconstruct the image in response to aprocess in which the video/image information is processed in theencoding apparatus illustrated in FIG. 2 . For example, the decodingapparatus 300 may derive the units/blocks based on block split-relatedinformation acquired from the bitstream. The decoding apparatus 300 mayperform decoding using the processing unit applied to the encodingapparatus. Therefore, the processing unit for the decoding may be, forexample, a coding unit, and the coding unit may be split according tothe quad-tree structure, the binary-tree structure, and/or theternary-tree structure from the coding tree unit or the maximum codingunit. One or more transform units may be derived from the coding unit.In addition, the reconstructed image signal decoded and output throughthe decoding apparatus 300 may be reproduced through a reproducingapparatus.

The decoding apparatus 300 may receive the signal output from theencoding apparatus illustrated in FIG. 2 in a form of the bitstream, andthe received signal may be decoded through the entropy decoder 310. Forexample, the entropy decoder 310 may derive information (e.g.,video/image information) necessary for the image reconstruction (orpicture reconstruction) by parsing the bitstream. The video/imageinformation may further include information about various parameter setssuch as an adaptation parameter set (APS), a picture parameter set(PPS), a sequence parameter set (SPS), and a video parameter set (VPS).In addition, the video/image information may further include generalconstraint information. The decoding apparatus may decode the picturefurther based on the information about the parameter set and/or thegeneral constraint information. The signaled/received information and/orsyntax elements to be described later in the present document may bedecoded through the decoding procedure and acquired from the bitstream.For example, the entropy decoder 310 may decode information within thebitstream based on a coding method such as an exponential Golomb coding,a CAVLC, or a CABAC, and output a value of the syntax element necessaryfor the image reconstruction, and the quantized values of theresidual-related transform coefficient. More specifically, the CABACentropy decoding method may receive a bin corresponding to each syntaxelement from the bitstream, determine a context model using syntaxelement information to be decoded and decoding information of theneighboring block and the block to be decoded or information of thesymbol/bin decoded in the previous stage, and generate a symbolcorresponding to a value of each syntax element by predicting theprobability of generation of the bin according to the determined contextmodel to perform the arithmetic decoding of the bin. At this time, theCABAC entropy decoding method may determine the context model and thenupdate the context model using the information of the decoded symbol/binfor a context model of a next symbol/bin. The information aboutprediction among the information decoded by the entropy decoder 310 maybe provided to the predictor (the inter predictor 332 and the intrapredictor 331), and a residual value at which the entropy decoding isperformed by the entropy decoder 310, that is, the quantized transformcoefficients and the related parameter information may be input to theresidual processor 320. The residual processor 320 may derive a residualsignal (residual block, residual samples, and residual sample array). Inaddition, the information about filtering among the information decodedby the entropy decoder 310 may be provided to the filter 350. Meanwhile,a receiver (not illustrated) for receiving the signal output from theencoding apparatus may be further configured as the internal/externalelement of the decoding apparatus 300, or the receiver may also be acomponent of the entropy decoder 310. Meanwhile, the decoding apparatusaccording to the present document may be called a video/image/picturedecoding apparatus, and the decoding apparatus may also be classifiedinto an information decoder (video/image/picture information decoder)and a sample decoder (video/image/picture sample decoder). Theinformation decoder may include the entropy decoder 310, and the sampledecoder may include at least one of the dequantizer 321, the inversetransformer 322, the adder 340, the filter 350, the memory 360, theinter predictor 332, and the intra predictor 331.

The dequantizer 321 may dequantize the quantized transform coefficientsto output the transform coefficients. The dequantizer 321 may rearrangethe quantized transform coefficients in a two-dimensional block form. Inthis case, the rearrangement may be performed based on a coefficientscan order performed by the encoding apparatus. The dequantizer 321 mayperform dequantization for the quantized transform coefficients using aquantization parameter (e.g., quantization step size information), andacquire the transform coefficients.

The inverse transformer 322 inversely transforms the transformcoefficients to acquire the residual signal (residual block, residualsample array).

The predictor 330 may perform the prediction of the current block, andgenerate a predicted block including the prediction samples of thecurrent block. The predictor 330 may determine whether the intraprediction is applied or the inter prediction is applied to the currentblock based on the information about prediction output from the entropydecoder 310, and determine a specific intra/inter prediction mode.

The predictor 330 may generate the predicted signal based on variousprediction methods to be described later. For example, the predictor 330may not only apply the intra prediction or the inter prediction for theprediction of one block, but also apply the intra prediction and theinter prediction at the same time. This may be called a combined interand intra prediction (CIIP). Further, the predictor 330 may be based onan intra block copy (IBC) prediction mode, or a palette mode in order toperform prediction on a block. The IBC prediction mode or palette modemay be used for content image/video coding of a game or the like, suchas screen content coding (SCC). The IBC basically performs prediction ina current picture, but it may be performed similarly to inter predictionin that it derives a reference block in a current picture. That is, theIBC may use at least one of inter prediction techniques described in thepresent document. The palette mode may be regarded as an example ofintra coding or intra prediction. When the palette mode is applied,information on a palette table and a palette index may be included inthe video/image information and signaled.

The intra predictor 331 may predict the current block with reference tothe samples within the current picture. The referenced samples may belocated neighboring to the current block according to the predictionmode, or may also be located away from the current block. The predictionmodes in the intra prediction may include a plurality of non-directionalmodes and a plurality of directional modes. The intra predictor 331 mayalso determine the prediction mode applied to the current block usingthe prediction mode applied to the neighboring block.

The inter predictor 332 may induce the predicted block of the currentblock based on the reference block (reference sample array) specified bythe motion vector on the reference picture. At this time, in order todecrease the amount of the motion information transmitted in the interprediction mode, the motion information may be predicted in units of ablock, a sub-block, or a sample based on the correlation of the motioninformation between the neighboring block and the current block. Themotion information may include a motion vector and a reference pictureindex. The motion information may further include inter predictiondirection (L0 prediction, L1 prediction, Bi prediction, or the like)information. In the case of the inter prediction, the neighboring blockmay include a spatial neighboring block existing within the currentpicture and a temporal neighboring block existing in the referencepicture. For example, the inter predictor 332 may configure a motioninformation candidate list based on the neighboring blocks, and derivethe motion vector and/or the reference picture index of the currentblock based on received candidate selection information. The interprediction may be performed based on various prediction modes, and theinformation about the prediction may include information indicating themode of the inter prediction of the current block.

The adder 340 may add the acquired residual signal to the predictedsignal (predicted block, prediction sample array) output from thepredictor (including the inter predictor 332 and/or the intra predictor331) to generate the reconstructed signal (reconstructed picture,reconstructed block, reconstructed sample array). As in the case wherethe skip mode is applied, if there is no residual for the block to beprocessed, the predicted block may be used as the reconstructed block.

The adder 340 may be called a reconstructor or a reconstructed blockgenerator. The generated reconstructed signal may be used for the intraprediction of a next block to be processed within the current picture,and as described later, may also be output through filtering or may alsobe used for the inter prediction of a next picture.

Meanwhile, a luma mapping with chroma scaling (LMCS) may also be appliedin the picture decoding process.

The filter 350 may apply filtering to the reconstructed signal, therebyimproving the subjective/objective image qualities. For example, thefilter 350 may apply various filtering methods to the reconstructedpicture to generate a modified reconstructed picture, and transmit themodified reconstructed picture to the memory 360, specifically, the DPBof the memory 360. Various filtering methods may include, for example, adeblocking filtering, a sample adaptive offset, an adaptive loop filter,a bidirectional filter, and the like.

The (modified) reconstructed picture stored in the DPB of the memory 360may be used as the reference picture in the inter predictor 332. Thememory 360 may store motion information of the block in which the motioninformation within the current picture is derived (decoded) and/ormotion information of the blocks within the previously reconstructedpicture. The stored motion information may be transferred to the interpredictor 332 to be utilized as motion information of the spatialneighboring block or motion information of the temporal neighboringblock. The memory 360 may store the reconstructed samples of thereconstructed blocks within the current picture, and transfer the storedreconstructed samples to the intra predictor 331.

In the present document, the exemplary embodiments described in thefilter 260, the inter predictor 221, and the intra predictor 222 of theencoding apparatus 200 may be applied equally to or to correspond to thefilter 350, the inter predictor 332, and the intra predictor 331 of thedecoding apparatus 300, respectively.

As described above, in performing video coding, a prediction isperformed to enhance compression efficiency. A predicted block includingprediction samples for a current block, that is, a target coding block,may be generated through the prediction. In this case, the predictedblock includes the prediction samples in a spatial domain (or pixeldomain). The predicted block is identically derived in the encodingapparatus and the decoding apparatus. The encoding apparatus may enhanceimage coding efficiency by signaling, to the decoding apparatus,information on a residual (residual information) between the originalblock not an original sample value itself of the original block and thepredicted block. The decoding apparatus may derive a residual blockincluding residual samples based on the residual information, maygenerate a reconstructed including reconstructed samples by adding theresidual block and the predicted block, and may generate a reconstructedpicture including the reconstructed blocks.

The residual information may be generated through a transform andquantization procedure. For example, the encoding apparatus may derivethe residual block between the original block and the predicted block,may derive transform coefficients by performing a transform procedure onthe residual samples (residual sample array) included in the residualblock, may derive quantized transform coefficients by performing aquantization procedure on the transform coefficients, and may signalrelated residual information to the decoding apparatus (through abitstream). In this case, the residual information may includeinformation, such as value information, location information, transformscheme, transform kernel, and quantization parameter of the quantizedtransform coefficients. The decoding apparatus may perform adequantization/inverse transform procedure based on the residualinformation, and may derive residual samples (or residual block). Thedecoding apparatus may generate a reconstructed picture based on thepredicted block and the residual block. Furthermore, the encodingapparatus may derive a residual block bydequantizing/inverse-transforming the quantized transform coefficientsfor reference to the inter prediction of a subsequent picture, and maygenerate a reconstructed picture.

In the present document, at least one of the quantization/thedequantization and/or the transform/the inverse transform may beomitted. If the quantization/dequantization is omitted, the quantizedtransform coefficient may be referred to as a transform coefficient. Ifthe transform/the inverse transform are omitted, the transformcoefficient may also be referred to as a coefficient or a residualcoefficient, or for unity of expression, also be still referred to asthe transform coefficient.

Further, in the present document, the quantized transform coefficientand the transform coefficient may be referred to as a transformcoefficient and a scaled transform coefficient, respectively. In thiscase, the residual information may include information about thetransform coefficient(s), and the information about the transformcoefficient(s) may be signaled through a residual coding syntax. Thetransform coefficients may be derived based on the residual information(or the information about the transform coefficient(s)), and the scaledtransform coefficients may be derived through the inverse transform(scaling) for the transform coefficients. The residual samples may bederived based on the inverse transform (transform) for the scaledtransform coefficients. This may be likewise applied to/expressed inother parts of the present document.

FIG. 4 exemplarily shows a hierarchical structure for a codedimage/video.

Referring to FIG. 4 , the coded image/video is divided into VCL (videocoding layer) that deals with an image/video decoding process anditself, a subsystem that transmits and stores the coded information, anda network abstraction layer (NAL) that exists between the VCL andsubsystems and is responsible for network adaptation functions.

The VCL may generate VCL data including compressed image data (slicedata), or generate parameter sets including a picture parameter set(Picture Parameter Set: PPS), a sequence parameter set (SequenceParameter Set: SPS), a video parameter set (Video Parameter Set: VPS)etc. or a supplemental enhancement information (SEI) messageadditionally necessary for the decoding process of an image.

In the NAL, a NAL unit may be generated by adding header information(NAL unit header) to a raw byte sequence payload (RBSP) generated in theVCL. In this case, the RBSP refers to slice data, parameter sets, SEImessages, etc. generated in the VCL. The NAL unit header may include NALunit type information specified according to RBSP data included in thecorresponding NAL unit.

As shown in FIG. 4 , the NAL unit may be divided into a VCL NAL unit anda Non-VCL NAL unit according to the RBSP generated in the VCL. The VCLNAL unit may mean a NAL unit including information (sliced data) aboutan image, and the Non-VCL NAL unit may mean a NAL unit containinginformation (parameter set or SEI message) necessary for decoding animage.

The above-described VCL NAL unit and Non-VCL NAL unit may be transmittedthrough a network by attaching header information according to a datastandard of the subsystem. For example, the NAL unit may be transformedinto a data form of a predetermined standard such as H.266/VVC fileformat, Real-time Transport Protocol (RTP), Transport Stream (TS), etc.and transmitted through various networks.

As described above, in the NAL unit, the NAL unit type may be specifiedaccording to the RBSP data structure included in the corresponding NALunit, and information on this NAL unit type may be stored and signaledin the NAL unit header.

For example, the NAL unit may be roughly classified into the VCL NALunit type and the Non-VCL NAL unit type depending on whether the NALunit includes information about the image (slice data). The VCL NAL unittype may be classified according to property and a type of a pictureincluded in the VCL NAL unit, and the Non-VCL NAL unit type may beclassified according to the type of a parameter set.

The following is an example of the NAL unit type specified according tothe type of parameter set included in the Non-VCL NAL unit type.

-   -   APS (Adaptation Parameter Set) NAL unit: Type for NAL unit        including APS    -   DPS (Decoding Parameter Set) NAL unit: Type for NAL unit        including DPS    -   VPS (Video Parameter Set) NAL unit: Type for NAL unit including        VPS    -   SPS (Sequence Parameter Set) NAL unit: Type for NAL unit        including SPS    -   PPS (Picture Parameter Set) NAL unit: Type for NAL unit        including PPS    -   PH (Picture header) NAL unit: Type for NAL unit including PH

The above-described NAL unit types have syntax information for the NALunit type, and the syntax information may be stored and signaled in theNAL unit header. For example, the syntax information may benal_unit_type, and NAL unit types may be specified by a nal_unit_typevalue.

Meanwhile, as described above, one picture may include a plurality ofslices, and one slice may include a slice header and slice data. In thiscase, one picture header may be further added to a plurality of slices(a slice header and a slice data set) in one picture. The picture header(picture header syntax) may include information/parameters commonlyapplicable to the picture. For example, one picture may be composed ofdifferent types of slices including intra coded slices (namely,I-slices) and/or inter coded slices (namely, P-slices and B-slices). Inthis case, a picture header may include information/parameters appliedto intra coded slices and inter coded slices. Alternatively, one picturemay be composed of one type of slice.

The slice header (slice header syntax) may includeinformation/parameters commonly applicable to the slice. The APS (APSsyntax) or PPS (PPS syntax) may include information/parameters commonlyapplicable to one or more slices or pictures. The SPS (SPS syntax) mayinclude information/parameters commonly applicable to one or moresequences. The VPS (VPS syntax) may include information/parameterscommonly applicable to multiple layers. The DPS (DPS syntax) may includeinformation/parameters commonly applicable to the entire video. The DPSmay include information/parameters related to concatenation of a codedvideo sequence (CVS). In this document, high level syntax (HLS) mayinclude at least one of the APS syntax, PPS syntax, SPS syntax, VPSsyntax, DPS syntax, picture header syntax, and slice header syntax.

In this document, the image/video information encoded in the encodingapparatus and signaled in the form of a bitstream to the decodingapparatus may include, as well as picture partitioning-relatedinformation in the picture, intra/inter prediction information, residualinformation, in-loop filtering information, etc. the informationincluded in the slice header, the information included in the pictureheader, the information included in the APS, the information included inthe PPS, the information included in the SPS, the information includedin the VPS, and/or the information included in the DPS. In addition, theimage/video information may further include information of the NAL unitheader.

Meanwhile, the encoding and decoding apparatus may encode/decode apicture by partitioning the picture into predetermined units. Forexample, the encoding and decoding apparatus may encode/decode thepicture by partitioning the picture into slices and/or tiles.

As described above, one picture may be partitioned into one or more tilerows and/or one or more tile columns. A tile is a rectangular areacomprising CTUs within a specific tile row and a specific tile column.CTUs included in one tile may be arranged based on specific scan order.For example, CTUs included in one tile may be arranged consecutivelybased on the raster scan order. A slice may consist of an integer numberof complete tiles or an integer number of consecutive CTU rows containedwithin a tile of a picture.

In this case, a vertical boundary of each slice within a picture may bea vertical boundary of a tile. A horizontal boundary of each slicewithin a picture may be a horizontal boundary of a tile or a horizontalboundary of a CTU within the tile. When the horizontal boundary of eachslice within a picture is not the horizontal boundary of a tile but thehorizontal boundary of a CTU within the tile, the tile within thepicture may be partitioned into a plurality of rectangular slices, andeach of the plurality of rectangular slices may be composed of aninteger number consecutive CTU rows.

Slices may be present in the raster scan slice mode and rectangularslice mode. In the raster scan slice mode, one slice may include one ormore tiles arranged in the raster scan order within a picture. Forrectangular slice mode, one slice may include an integer number ofcomplete tiles forming a rectangular area within a picture or include aninteger number of consecutive CTU rows within one tile forming arectangular area within a picture. Tiles within a rectangular slice maybe scanned based on the raster scan order within the area of therectangular slice.

FIG. 5 shows one embodiment in which a picture is partitioned intoslices and tiles.

Here, a thick line represents the boundary of a slice, a thin linerepresents the boundary of a tile, and a dotted line represents theboundary of a CTU. Referring to FIG. 5 , a picture consists of 216(18×12) CTUs, three tile columns, and four tile rows. Accordingly, thepicture comprises 12 tiles and 3 slices based on the raster scan slicemode. Here, among the three slices, slice 1 based on the raster scanorder is composed of two complete tiles based on the raster scan order,slice 2 is composed of 5 complete tiles based on the raster scan order,slice 3 is composed of 5 complete tiles based on the raster scan order.The vertical boundary of each of the three slices is composed ofvertical boundaries of tiles within the picture. The horizontal boundaryof each of the three slices is composed of the horizontal boundaries oftiles (within-tile CTUs) within the picture.

FIG. 6 shows one embodiment in which a picture is partitioned intoslices and tiles.

In the same manner, a thick line represents the boundary of a slice, athin line represents the boundary of a tile, and a dotted linerepresents the boundary of a CTU. Referring to FIG. 6 , a pictureconsists of 216 (18×12) CTUs, six tile columns, and four tile rows.Accordingly, the picture comprises 24 tiles and 9 slices based on therectangular slice mode. Here, among the 9 slices, each of slice 1, 2, 3,7, 8, and 9 based on the raster scan order is composed of two completetiles, and each of slice 4, 5, and 6 based on the raster scan order iscomposed of 4 complete tiles. The vertical boundary of each of the 9slices is composed of vertical boundaries of tiles within the picture.The horizontal boundary of each of the 9 slices is composed of thehorizontal boundaries of tiles (within-tile CTUs) within the picture.

FIG. 7 shows one embodiment in which a picture is partitioned intoslices and tiles.

In the same manner, a thick line represents the boundary of a slice, athin line represents the boundary of a tile, and a dotted linerepresents the boundary of a CTU. Referring to FIG. 7 , a pictureconsists of 216 (18×12) CTUs, three tile columns, and two tile rows.Accordingly, the picture comprises 6 tiles and 7 slices based on therectangular slice mode. Here, among the 7 slices, slice 1 based on theraster scan order is composed of two complete tiles, each of slice 2, 3,4, and 5 based on the raster scan order is composed of 3 consecutive CTUrows included within a tile, and slice 6 and 7 based on the raster scanorder comprises one complete tile. The vertical boundary of each of the7 slices is composed of vertical boundaries of tiles within the picture.The horizontal boundary of each of slice 1, 6, and 7 among the 7 slicesis composed of the horizontal boundaries of tiles (within-tile CTUs)within the picture. The upper horizontal boundary of each of slice 2 and3 among the 7 slices is composed of horizontal boundaries of tiles(within-tile CTUs) within the picture, and the lower horizontal boundaryis composed of horizontal boundaries of CTUs within tiles, which do notconstitute the horizontal boundary of a tile. The upper horizontalboundary of each of slice 4 and 5 among the 7 slices is composed ofhorizontal boundaries of CTUs within tiles, which do not constitute thehorizontal boundary of a tile, and the lower horizontal boundary iscomposed of horizontal boundaries of tiles (within-tile CTUs) within thepicture.

As described above, the video encoding apparatus and the video decodingapparatus may process (encode/decode) a picture by partitioning thepicture in slice, tile, and/or CTU row units. At this time, since thevideo encoding apparatus/video decoding apparatus requires a relativelyhigher amount of computation in the process of compressing anddecompressing data than other multimedia technologies, when the encodingapparatus/decoding apparatus is equipped with a multi-core processor ora multi-processor, the encoding apparatus/decoding apparatus may performencoding/decoding independently and in parallel for partition areas ofdifferent units.

On the other hand, when the encoding/decoding apparatus has asingle-core processor, the encoding/decoding apparatus may not performparallel processing and thus reduce/adjust the memory load for singleprocessing.

When the encoding apparatus/decoding apparatus has a multi-coreprocessor or a multi-processor, the encoding apparatus/decodingapparatus may use parallelization techniques to increase codingefficiency. For example, the parallelization techniques may includeWavefront Parallel Processing (WPP), Tiles, and the like.

WPP may support slices in a picture to be processed (encoded/decoded) inparallel. In other words, WPP may support parallel processing(encoding/decoding) of CTU rows in a picture by partitioning the pictureinto CTU rows. In addition, WPP enables parallel processing of entropycoding for a plurality of sub-bitstreams within slice data by generatinga sub-bitstream in CTU row units for entropy coding and transferring thestart position of the sub-bitstream in the slice header. In thisrespect, to perform parallel processing of entropy coding in units ofCTU rows, CABAC should be applied independently for each CTU row, andthe CABAC should synchronize a context model continuously while the CTUis coded within a slice. To minimize degradation of CABAC codingefficiency, when a CTU at the upper right side of the first CTU of eachCTU row is synchronized after being encoded/decoded, WPP may initializethe context model through the synchronized CABAC context before codingeach CTU row.

Through the above operation, it is possible to minimize degradation ofcoding efficiency compared to the case of independently initializing theCABAC context in units of CTU rows. In other words, unlike tiles andslices, since WPP performs intra prediction or inter prediction byutilizing information on the blocks already coded in the upper CTU row,parallel processing (encoding/decoding) of video/images is made possiblewhile degradation of coding efficiency is minimized.

FIG. 8 exemplarily shows initialization of a CABAC context model forWPP.

For example, referring to FIG. 8 , entropy encoding/decoding of apicture may be processed for each sub-bitstream related to each CTU row.For example, when entropy encoding/decoding for a sub-bitstreamcorresponding to the n (where n is an integer)-th CTU row is processed,entropy encoding/decoding for the sub-bitstream corresponding to the(n+1)-th CTU row may be processed.

Specifically, when entropy encoding/decoding for the second CTU of thesub-bitstream corresponding to the n-th CTU row is completed, relatedCABAC context may be stored. Afterward, the first CTU of a sub-bitstreamcorresponding to the (n+1)-th CTU row may be entropy encoded/decodedbased on the CABAC context for the second CTU of the n-th sub-bitstream.

Meanwhile, the tile technology may support parallel processing(encoding/decoding) of tiles in a picture by partitioning the pictureinto tiles. In addition, the tile technology enables parallel processingof entropy coding for a plurality of sub-bitstreams within slice data bygenerating a sub-bitstream in tile units for entropy coding andtransferring the start position of the sub-bitstream in the sliceheader. When a picture is partitioned into the same number of slices ortiles, the number of CTUs positioned on the partition boundary issmaller when it is partitioned into tiles compared to the case when itis partitioned into slices. Also, since a tile transmits only thepartition information of the tile through a PPS, it may be effective interms of coding efficiency compared to slice partitioning, which uses aslice header additionally for each partition area.

To enable the parallel processing above, entry point related informationmay be signaled. Signaling the entry point related information maysupport a decoding apparatus to directly access a start point of datasegments of a coded slice within a NAL unit. Here, the start point ofthe data segments may be the start point of tiles included in the sliceor the start point of CTU rows included in the slice.

In other words, the entry point may mean an access point on a bitstreamfor performing encoding/decoding in parallel using WPP or tiletechnology. Also, the entry point may be a start point of eachsub-bitstream for encoding/decoding to be started. For example, theentry point may be a start point of each WPP sub-bitstream or each tilethat is a target point of parallel processing on the bitstream. When theencoding apparatus/decoding apparatus has a multi-core processor or amulti-processor, the encoding apparatus/decoding apparatus may performencoding/decoding independently and in parallel at different entrypoints. Although WPP and tile technology are different in theencoding/decoding technology intended to be applied, information relatedto the entry point of a CTU row (sub-bitstream corresponding to the CTUrow) to which WPP is applied and information related to the entry pointof a tile may be signaled in the same manner.

In other words, it is important to signal each CTU row to which WPP isapplied for parallel processing or information related to the entropypoint of a sub-bitstream corresponding to each CTU row and to signaleach tile or information related to the entropy point of a sub-bitstreamcorresponding to each tile. Here, the information related to the entrypoint may be referred to as entry point related information.

However, in the related art, in case that both WPP and tile technologyare applied to a slice, entry point offset information of a CTU row(substream corresponding to the CTU row) to which the WPP is applied andentry point offset information of the tile have been processed in amanner that they are all signaled or they are not signaled in all. Thatis, if it is specified that signalling of the entry point offsetinformation is present in a state where one slice includes a pluralityof sub slices (a plurality of tiles or a plurality of CTU rows when theWPP is enabled), all pieces of entry point offset information related tothe one slice have been processed to be signaled through a slice headerof the one slice.

In this case, it may be considered that indication representing whetherthe entry point offset information is signaled is separated intoindication representing whether the entry point offset information forthe tile is signaled and indication representing whether the entry pointoffset information for the WPP is signaled. For example, the entry pointoffset information for the tile may be signaled through a slice headerof a specific slice including a plurality of tiles. In this case, theentry point offset information for the WPP may be selectively signaledthrough the slice header of the specific slice. That is, the entry pointoffset information for the WPP may be signaled through the slice headerof the specific slice, or may not be signaled.

However, the design for separating into the indication representingwhether the entry point offset information for the tile is signaled andthe indication representing whether the entry point offset informationfor the WPP is signaled has not been currently supported.

As described above, the tile (tile technology) and the WPP aretechnologies being applied to support parallel processing ofencoding/decoding. However, if the tile and the WPP are applied to oneslice at the same time, the encoding/decoding operation of thecorresponding slice may become unnecessary and complicated. It may bepreferable to limit the simultaneous application of the technologies ofthe tile and the WPP to one slice so that the encoding/decodingoperation is not implemented to be complicated.

In relation to this, embodiments of the present document may include oneor more of the following features.

1) If signaling of the entry point offset information is present in astate where the entry point offset information is allowed to besignaled, it may be possible to signal all pieces of entry point offsetinformation (if the tile and the WPP are enabled, all pieces of entrypoint offset information for the tile and the WPP).

2) Indications representing whether the entry point offset informationon the different technologies (e.g., tile, WPP, and the like) aresignaled may be independent of each other. In case that both the tileand the WPP are supported (e.g., in the same codec and in the sameprofile), the indication representing whether the entry point offsetinformation for the file is signaled may be different from theindication representing whether the entry point offset information forthe WPP is signaled.

3) In case that a picture is divided into a plurality of tiles, a tileentry point offset present flag indicating whether the entry pointoffset information for the file is present in the slice header of theslice including the plurality of tiles may be present. For example, thetile entry point offset present flag may be represented astile_entry_point_offsets_present_flag.

-   -   For example, only in case that the slice includes a plurality of        tiles, the entry point offset information for the tile can be        present in the slice header of the slice.    -   As another example, the signaling condition of the entry point        offset information for the tile may be limited to a case where        at least one slice including the plurality of tiles is present.

4) In case that a picture is divided into a plurality of tiles, it maybe specified that the entry point offset information for the tile ispresent in the slice header of the slices including the plurality oftiles.

5) In case that the WPP is enabled (i.e., if the value of theentropy_coding_sync_enabled_flag is 1), the WPP entry point offsetpresent flag indicating whether the entry point offset information forthe WPP is present may be present. For example, the WPP entry pointoffset present flag may be represented aswpp_entry_point_offsets_present_flag.

-   -   For example, only in case that the slice includes a plurality of        CTUs including a plurality of CTU rows, the entry point offset        information for the WPP may be present in the slice header of        the slice.

6) In case that WPP is enabled, it may be specified that the entry pointoffset information for the WPP is present.

7) In case that the entropy_coding_sync_enabled_flag related to whetherthe WPP is enabled is included in a parameter set (PPS), and the WPP isenabled (i.e., if the value of the entropy_coding_sync_enabled_flag is1), each slice of a picture referring to the parameter set may belimited not to include a plurality of tiles.

-   -   In this case, the slices including CTU rows being a subset in        the tile do not violate the limit.

8) In case that at least one slice including a plurality of tiles ispresent, the WPP may be limited not to be enabled.

Here, the entry point related information may include various kinds ofinformation according to an embodiment of the present document. Forexample, the entry point related information may include at least one ofno_pic_partition_flag, entropy_coding_sync_enabled_flag,entry_point_offsets_present_flag, tile_entry_point_offsets_present_flag,wpp_entry_point_offsets_present_flag, offset_len_minus1,entry_point_offset_minus1, and/or num_entry_point_offsets. Further, theconfiguration of the entry point related information, the parsingposition, and the signaling condition may be determined according to anembodiment of the present document. For example, video/image informationmay include a high level syntax (HLS), and the HLS may include the entrypoint related information.

According to an embodiment proposed in the present document, the entrypoint related information may be signaled as follows.

For example, the entry point related information may include offsetlength information and entry point offset information. For example, theoffset length information may be related to the number of bits of theentry point offset information. That is, the offset length informationmay indicate/represent the number of bits of the entry point offsetinformation.

For example, the offset length information may be represented in theform of an offset_len_minus1 syntax element. For example, the value ofthe offset_len_minus1 syntax element of +1 may specify the number ofbits of the entry point offset information (e.g.,entry_point_offset_minus1 syntax element).

Further, the entry point offset information may represent an offsetbetween two entry points. As an example, the entry point offsetinformation may represent the offset between the two entry points in theunit of a byte.

For example, the entry point offset information may be represented inthe form of an entry_point_offset_minus1 syntax element. For example,the value of the entry_point_offset_minus1 syntax element of +1 mayspecify the offset in the unit of a byte.

Based on the offset length information and the entry point offsetinformation, at least one entry point that is present in the currentpicture may be derived.

In this case, according to an embodiment having been proposed in therelated art in relation to signaling of entry point offsets, the entrypoint related information may include an entry point offset presentflag. For example, the entry point offset present flag may be related towhether the entry point offsets are signaled. That is, the entry pointoffset present flag may indicate/represent whether the entry pointoffsets are signaled.

For example, the entry point offset present flag may be represented inthe form of an entry_point_offsets_present_flag syntax element. Forexample, the entry_point_offsets_present_flag syntax element may specifywhether the entry point offsets are signaled.

If the value of the entry point offset present flag is 1, the number ofentry points in the current slice may be derived. If the number of thederived entry points is larger than 0, the offset length information andthe entry point offset information may be configured/included in theslice header of the current slice.

In relation to this, according to the one embodiment proposed in therelated art, the slice header may include syntax in Table 1 below. Thesyntax in Table 1 below may be a part of the slice header.

TABLE 1 Descriptor slice_header( ){  . . .  if entry pointoffsets_present_flag && NumEntryPoints >0 ) {   offset_len_minus1 ue(v)  for i = 0; i < NumEntryPoints; i++ )    entry_point_offset_minus1[ i ]u(v)  }  . . . }

Referring to Table 1 above, if the value of the syntax elemententry_point_offsets_present_flag related to the entry point offsetpresent flag is 1, a variable NumEntryPoints related to the number ofentry points present in the current slice may be derived as in Table 2below.

TABLE 2 NumEntryPoints = 0 for( i = 1; i <NumCtuInCurrSlice;i++) { CtbAddrInRs = CtbAddrInCurrSlice[ i ]  CtbAddrX = ( CtbAddrInRs %PicWidthInCtbsY )  CtbAddrY = ( CtbAddrInRs / PicWidthInCtbsY )  ifCtbAddrX = = CtbToTileColBd[ CtbAddrX ] &&   ( CtbAddrY = =CtbToTileRowBd[ CtbAddrY ] | | entropy_coding_sync_enabled_flag) )  NumEntryPoints++ }

Here, semantics of the syntax element included in Table 1 above may berepresented, for example, as in Table 3 below.

TABLE 3 offset_len_minus1 plus 1 specifies the length, in bits, of theentry_point_offset_minus1[ i ] syntax elements. The value of offset_len_minus1 shall be in the range of 0 to 31, inclusive.entry_point_offset_minus1[ i ] plus 1 specifies the i-th entry pointoffset in bytes, and is represented by offset_len_minus1 plus 1 bits.The slice data that follow the slice header consists of NumEntryPoints +1 subsets, with subset index values ranging framO to NumEntryPoints,inclusive. The first byte of the slice data is considered byte 0, Whenpresent, emulation prevention bytes that appear in the slice dataportion of the coded slice NAI unit are counted as part of the slicedata for purposes of subset identification. Subset 0 consists of bytes 0to entry_point_offset_minus1[ 0 ], inclusive, of the coded slice data,subset k, withk in the range of 1 to NumEntryPoints − 1, inclusive,consists of bytes firstByte[ k ] to lastByte[ k ], inclusive, of thecoded slice data with firstByte[ k ]and. lastByte[ k ] defined as:firstByte[ k ] = Σ^(k) _(n=1)(entry_point_offset_minus1[ n − 1] + 1)lastByte[k] = firstByte[ k ] + entry point_offset_minus[ k] The lastsubset (with subset index equal to N umEntryPoints) consists of theremaining bytes of the coded slice data. When entropy _coding_sync_enabled_flag is equal to 0 and the slice contains one or morecomplete tiles, each, subset shall consist of all coded bits, of allCTOs in the: slice that are within the same file, and the number ofsubsets (i.e., the value of NumEntryPoints + 1) shall be equal to thenumber of tiles: in the slice. When entropy_coding__sync_enabled_flag isequal to 0 and the slice contains a subset of CTU rows from a singletile, the NumEntryPoints shall be 0, and the number of subsets shallbe 1. The subset shall consist of all coded bits of all CTUs in theslice. When entropy_coding_sync_enabled flag is equal to 1, each subsetit with k in the range of 0 to NumEntryPoints, inclusive, shall consistof all coded bits of all CTUs in a CTU row within a tile, and the numberof subsets] i.e., the value of NumEntryPoints + 1) s hall be equal to-the total nu mber of tile- specific CTU rows in the slice.

In contrast to this, according to an embodiment proposed in the presentdocument, the entry point related information may include a WPP entrypoint offset present flag. For example, the WPP entry point offsetpresent flag may be related to whether the entry point offsets for theWPP are signaled. That is, the WPP entry point offset present flag mayindicate/represent whether the entry point offsets for the WPP aresignaled.

For example, the WPP entry point offset present flag may be representedin the form of a wpp_entry_point_offsets_present_flag syntax element.For example, the wpp_entry_point_offsets_present_flag syntax element mayspecify whether entry point offsets for the WPP are signaled.

If the value of the WPP entry point offset present flag is 1, the offsetlength information and the entry point offset information may beconfigured/included in the slice header for the current slice.

Further, according to the one embodiment proposed in the presentdocument, the entry point related information may include a no-picturepartition flag. For example, the no-picture partition flag may berelated to whether the no-picture partitioning is applied to the currentpicture. That is, the no-picture partition flag may indicate/representwhether the no-picture partitioning is applied to the current picture.

For example, the no-picture partition flag may be represented in theform of a no_pic_partition_flag syntax element. For example, theno_pic_partition_flag syntax element may specify whether the no-picturepartitioning is applied to the current picture.

If the value of the no-picture partition flag is not 1, the offsetlength information and the entry point offset information may beconfigured/included in the slice header for the current slice.

In relation to this, the slice header may include syntax in Table 4below. The syntax in Table 4 below may be a part of the slice header.

TABLE 4 Descriptor sliceheader ) {  . . .   if ( (!no_pic_partition_flag | | wpp_entry_point_offsets_present_flag ) &&    NumEntryPoints > 0 ) {    offset_len_minus1 ue(v)    for( i = 0; i <NumEntryPoints, i++ )     entry_point_offset_minus1[ i ] u(y)  }  . . .)

In this case, a variable NumEntryPoints included in the syntax of Table4 above may be related to the number of entry points present in thecurrent slice. That is, the variable NumEntryPoints mayindicate/represent the number of entry points present in the currentslice. In relation to this, semantics of a syntax element included inthe syntax of Table 4 above may be represented, for example, as in Table3 above.

That is, the value of the offset_len_minus1 syntax element of +1 mayrepresent the number of bits of the entry point offset information(e.g., entry_point_offset_minus1 syntax element). The offset_len_minus1syntax element may be called the offset length information, and may beincluded in the slice header. That is, the offset length information maybe signaled through the slice header.

The entry_point_offset_minus1[i] syntax element may represent an offsetbetween two entry points. The entry_point_offset_minus1[i] syntaxelement may be called the entry point offset information, and may beincluded in the slice header. That is, the entry point offsetinformation may be signaled through the slice header.

Here, the no_pic_partition_flag syntax element may represent whether theno-picture partitioning is applied to the current picture based onwhether the value thereof is 0 or 1. The no_pic_partition_flag syntaxelement may be called the no-picture partition flag.

The wpp_entry_point_offsets_present_flag syntax element may representwhether the entry point offset information for the WPP is present basedon whether the value thereof is 0 or 1. Thewpp_entry_point_offsets_present_flag syntax element may be called theWPP entry point offset present flag.

According to the one embodiment, if the value of the WPP entry pointoffset present flag is 1, the offset length information and the entrypoint offset information may be included in the slice header to besignaled. If the value of the WPP entry point offset present flag is not1, the offset length information and the entry point offset informationmay not be present.

Further, if the value of the no-picture partition flag is not 1, theoffset length information and the entry point offset information may beincluded in the slice header to be signaled. If the value of theno-picture partition flag is 1, the offset length information and theentry point offset information may not be present.

Further, according to the one embodiment, if the value of the variableNumEntryPoints related to the number of entry points present in thecurrent slice is larger than 0, the offset length information and theentry point offset information may be included in the slice header to besignaled. If the value of the variable NumEntryPoints is 0, the offsetlength information and the entry point offset information may not bepresent.

In this case, the offset length information and the entry point offsetinformation may be signaled without checking the value of the entrypoint offset present flag proposed in the related art.

According to the one embodiment proposed in the present document, theentry point related information may include an entropy codingsynchronization enabled flag. For example, the entropy codingsynchronization enabled flag may be related to whether theabove-described WPP is applied to the current picture. That is, theentropy coding synchronization enabled flag may indicate/representwhether the above-described WPP is applied to the current picture.

As a detailed example, in case that k (k is an integer) CTU rows areincluded in a slice, and coding for a second CTU of the m (m is aninteger that is smaller than k)-th row is completed, the entropy codingsynchronization enabled flag may be related to whether coding for afirst CTU of the (m+1)-th row is performed based on the synchronizedcontext of the second CTU of the m-th row. That is, in case that k (k isan integer) CTU rows are included in a slice, and coding for the secondCTU of the m (m is an integer that is smaller than k)-th row iscompleted, the entropy coding synchronization enabled flag mayindicate/represent whether the coding for the first CTU of the (m+1)-throw is performed based on the synchronized context of the second CTU ofthe m-th row.

For example, the entropy coding synchronization enabled flag may berepresented in the form of an entropy_coding_sync_enabled_flag syntaxelement. For example, the entropy_coding_sync_enabled_flag syntaxelement may specify whether the above-described WPP is applied to thecurrent picture. Further, in case that k (k is an integer) CTU rows areincluded in the slice, and the coding for the second CTU of the m (m isan integer that is smaller than k)-th row is completed, theentropy_coding_sync_enabled_flag syntax element may specify whether thecoding for the first CTU of the (m+1)-th row is performed based on thesynchronized context of the second CTU of the m-th row.

In relation to this, according to the one embodiment proposed in thepresent document, the PPS may include the syntax in Table 5 below. Thesyntax in Table 5 below may be a part of the PPS.

TABLE 5 Descriptor pic_parameter_set _rbsp( ) {  . . . no_pic_partition_flag u(1)  if( !no_pic_partition_fag ) {   . . .  } entropy_coding_syne_enabled_flag u(1)  ifentropy_coding_sync_enabled_flag)   wpp_entry_point_offsets_present_flagu(1)  . . . }

In this case, semantics of the syntax elements included in the syntax inTable 5 above may be represented, for example, as in Table 6 below.

TABLE 6 no_pic_partition_flag equal to 1 specifies that no picturepartitioning is applied to each picture referring to the PPS.t_pic_partition_Dag equal to 0 specifies that each picture referring tothe PBS might be partitioned into more than one tile or slice.entropy_coding_sync_enabled_flag equal to 1. specifies that a specificsynchronization process for context variables is invoked before decodingthe CTUthat includes the first CTB of a row of CTBs in each tile in eachpicture referring to the PPS, and a specific storage process for contextvariables is invoked after decoding the CTU that includes the first CTBof a row of CTBs in each tile i each picture referring to the PPS.entropy _coding_sync_enabled_flag equal to 0 specifies that no specificsynchronization process for context variables is required to be invokedbefore decoding the CTU that includes the first CTB of a row of CTBs ineach tile in each picture referring to the BBS, and no specific storageprocess for context variables is required to be invoked after decodingthe CTU that includes the first CTB of a row of CTBs in each tile ineach picture referring to the PBS. ( Whenentropy_coding_sync_enabled_flag is equal to 1, the so-called wavefrontparallel processing (WPP) is enabled.)wpp_entry_point_offsets_present_flag equal to 1 specifies 'tat WPP entrypoint offsets signalling may be prezentinthe slice headers of picturesreferring to the PPS wpp_entry_point_offsets_present_flag equal to 0specifies that WPP entry point offsets signalling are not present in theslice headers of pictures referring to the BPS. When not present thevalue of wpp_ entry point offsets_present_ flag is inferred to be equalto 0.

That is, as described above, the no_pic_partition_flag syntax elementmay represent whether the no-picture partitioning is applied to thecurrent picture based on whether the value thereof is 0 or 1. Theno_pic_partition_flag syntax element may be called the no-picturepartition flag, and may be included in the PPS. That is, the no-picturepartition flag may be signaled in the PPS (or PPS level). If the valueof the no-picture partition flag that is signaled in the PPS is 1,no-picture partitioning may be applied for the pictures referring to thePPS.

The entropy_coding_sync_enabled_flag syntax element may representwhether the above-described WPP is applied to the current picture basedon whether the value thereof is 0 or 1. Theentropy_coding_sync_enabled_flag syntax element may be called theentropy coding synchronization enabled flag, and may be included in thePPS. That is, the entropy coding synchronization enabled flag may besignaled in the PPS (or PPS level). If the value of the entropy codingsynchronization enabled flag that is signaled in the PPS is 1, theabove-described WPP may be applied for the pictures referring to thePPS.

As described above, the wpp_entry_point_offsets_present_flag syntaxelement may represent whether the entry point offset information for theWPP is present based on whether the value thereof is 0 or 1. Thewpp_entry_point_offsets_present_flag syntax element may be called theWPP entry point offset present flag, and may be included in the PPS.That is, the WPP entry point offset present flag may be signaled in thePPS (or PPS level). If the value of the WPP entry point offset presentflag that is signaled in the PPS is 1, the entry point offsetinformation for the WPP may be present for the pictures referring to thePPS.

According to the one embodiment, if the value of the entropy codingsynchronization enabled flag is 1, the WPP entry point offset presentflag may be included in the PPS to be signaled. In contrast, if thevalue of the entropy coding synchronization enabled flag is not 1, theWPP entry point offset present flag may not be present. For example, ifthe WPP entry point offset present flag is not present, the value of theWPP entry point offset present flag may be derived as 0.

In this case, unlike the entry point offset present flag proposed in therelated art, the WPP entry point offset present flag may be signaledwithout checking the value of the no-picture partition flag.

As described above, by signaling the WPP entry point offset present flagrather than the entry point offset present flag, it is possible tosignal only the entry point offsets for the WPP instead of signaling allthe entry point offsets related to parallelization technologies (WPP andtile) being applied to the current picture. Through this, it can besupported to derive an effect of enhancing the coding efficiency that isthe original purpose of encoding/decoding parallel processing while theencoding/decoding apparatus is not complicatedly implemented.

In relation to this, according to the one embodiment proposed in thepresent document, only in case that the current slice is composed of aplurality of CTUs included in a plurality of CTU rows, the WPP entrypoint offset present flag may be able to be included in the PPS.

Further, according to the one embodiment, in case that the WPP entrypoint offset present flag is included in the PPS, the slices in thepicture referring to the PPS can be limited not to be composed of aplurality of tiles.

According to another embodiment proposed in the present document, theentry point related information may further include a tile entry pointoffset present flag. For example, the tile entry point offset presentflag may be related to whether the entry point offsets for the tile aresignaled. That is, the tile entry point offset present flag mayindicate/represent whether the entry point offsets for the tile aresignaled.

For example, the tile entry point offset present flag may be representedin the form of a tile_entry_point_offsets_present_flag syntax element.For example, the tile_entry_point_offsets_present_flag syntax elementmay specify whether the entry point offsets for the tile are signaled.

In relation to this, if the value of the tile entry point offset presentflag is 1, the offset length information and the entry point offsetinformation may be configured/included in the slice header for thecurrent slice.

For example, the slice header may include syntax in Table 7 below. Thesyntax in Table 7 below may be a part of the slice header.

TABLE 7 Descriptor slice_header( ){  . . .  if( (tile_entry_point_offsets_present_flag | |wpp_entry_point_offsets_present_flag) &&    NumEntryPsints > 0 ) {  offset_len_minus1 ue(v)   for( i = 0; i < NumEntryPoints; i++ )   entry_point_offset_minus1[ i ] u(v)  }  . . . }

In this case, as described above, the variable NumEntryPoints includedin the syntax of Table 7 above may be related to the number of entrypoints being present in the current slice. That is, the variableNumEntryPoints may indicate/represent the number of entry points beingpresent in the current slice. In relation to this, semantics of a syntaxelement included in the syntax of Table 7 above may be represented, forexample, in the same manner as in Table 3 above.

That is, the tile_entry_point_offsets_present_flag syntax element mayrepresent whether the entry point offset information for the tile ispresent based on whether the value thereof is 0 or 1. Thetile_entry_point_offsets_present_flag syntax element may be called thetile entry point offset present flag.

According to the one embodiment, if the value of the tile entry pointoffset present flag is 1, the offset length information and the entrypoint offset information may be included in the slice header to besignaled. If the value of the tile entry point offset present flag isnot 1, the offset length information and the entry point offsetinformation may not be present.

Further, if the value of the entry point offset present flag for the WPPis 1, the offset length information and the entry point offsetinformation may be included in the slice header to be signaled. If thevalue of the entry point offset present flag for the WPP is not 1, theoffset length information and the entry point offset information may notbe present.

Further, according to the one embodiment, if the value of the variableNumEntryPoints related to the number of entry points being present inthe current slice is larger than 0, the offset length information andthe entry point offset information may be included in the slice headerto be signaled. If the value of the variable NumEntryPoints is 0, theoffset length information and the entry point offset information may notbe present.

In this case, the offset length information and the entry point offsetinformation may be signaled without checking the value of the entrypoint offset present flag proposed in the related art.

In relation to this, according to the one embodiment proposed in thepresent document, the PPS may include syntax in Table 8 below. Thesyntax in Table 8 below may be a part of the PPS.

TABLE 8 Descriptor picparameter_set_rbsp( ) {  . . . no_pic_partition_flag u(1)  if Ino_pic_partition_flag) {   . . .  } entropy_coding_sync_enabled_flag u(1)  if( !no_pic_partition_flag)  tile_entry_point_offsets_present_flag u(1)  if(entropy_coding_sync_enabled_flag )  wpp_entry_point_offsets_present_flag u(1)  . . . }

In this case, semantics of a syntax element included in the syntax ofTable 8 above may be represented, for example, as in Table 9 below.

tile_entry_point_offsets_present_flag equal to 1 specifies that tileentry point offsets signalling may be present in the slice headers ofpictures referring to the PPS. tile_entry_point_offsets_present_flagequal to 0 specifies that tile entry point offsets signalling are notpresent in the slice headers of pictures referring to the PPS. When notpresent, the- value of tile_entry point _offsets_ present flag isinferred to be equal to 0. wpp_entry_point _offsets_present_flag equalto 1 specifies that WPP enry point offsets signalling may be present inthe slice headers of pictures referring to the PPSwpp_entry_point_offets_present_flag equal to 0 specifies that WPP entrypoint offsets signalling are not present in the slice headers ofpictures referring to the PPS. When not present, the valueofwpp_entry_point_offsets_present_flagis inferred to be equal to 0.

That is, as described above, the tile entry_point_offsets_present_flagsyntax element may represent whether the entry point offset informationfor the tile is present based on whether the value thereof is 0 or 1.The tile_entry_point_offsets_present_flag syntax element may be calledthe tile entry point offset present flag, and may be included in thePPS. That is, the tile entry point present flag may be signaled in thePPS (or PPS level). If the value of the tile entry point offset presentflag that is signaled in the PPS is 1, the entry point offsetinformation for the pictures referring to the PPS may be present.

According to the one embodiment, if the value of the no-picturepartition flag is not 1, the tile entry point offset present flag may beincluded in the PPS to be signaled. In contrast, if the value of theno-picture partition flag is 1, the tile entry point offset present flagmay not be present. For example, if the tile entry point offset presentflag is not present, the value of the tile entry point offset presentflag may be derived as 0.

As described above, by separately signaling the tile entry point offsetpresent flag and the WPP entry point offset present flag, rather thanthe entry point offset present flag, it is possible to separately theentry point offsets for respective technologies instead of signaling allthe entry point offsets related to parallelization technologies (WPP andtile) being applied to the current picture. Through this, it can besupported to derive an effect of enhancing the coding efficiency that isthe original purpose of encoding/decoding parallel processing while theencoding/decoding apparatus is not complicatedly implemented.

In relation to this, according to the one embodiment proposed in thepresent document, only in case that the current slice is composed of aplurality of tiles, the tile entry point offset present flag may be ableto be included in the PPS.

Further, according to the one embodiment, in case that at least oneslice that is composed of a plurality of tiles in the current picture ispresent, it may be limited that the WPP is not applied to the currentslice.

The drawings in the following have been made to illustrate one specificembodiment of the present document. The names of specific apparatus orspecific signals/messages/fields disclosed in the drawings have beenchosen for an illustrative purpose only; therefore, technical featuresof the present document are not limited to the specific names used inthe following drawings.

FIGS. 9 and 10 illustrate an example of a video/image encoding methodand related components according to an embodiment(s) of the presentdocument. The method disclosed in FIG. 9 may be performed by theencoding apparatus disclosed in FIG. 2 . Specifically, for example, S900and S910 of FIG. 9 may be performed by the image partitioner 210 of theencoding apparatus, and S920 of FIG. 9 may be performed by the entropyencoder 240 of the encoding apparatus. The method disclosed in FIG. 9may include the embodiments described in the present document.

Referring to FIG. 9 , the encoding apparatus derives at least one entrypoint for a current picture S900. The encoding apparatus may partitionan input image (or a picture or a frame) into predetermined units. Forexample, the encoding apparatus may partition an input image intoslices, tiles, or CTU row units. At this time, for example, when WPP isapplied to the current picture, the encoding apparatus may derive atleast one entry point corresponding to at least one CTU row constitutingthe current picture. In another example, when tile technology is appliedto the current picture, the encoding apparatus may derive at least oneentry point corresponding to at least one tile constituting the currentpicture.

The encoding apparatus generates entry point related information basedon the at least one entry point (S910). For example, the entry pointrelated information may include at least one of a no-picture partitionflag, an entropy coding synchronization enabled flag, a WPP entry pointoffset present flag, a tile entry point offset present flag, offsetlength information, and/or entry point offset information. For example,the entry point related information may include at least one ofno_pic_partition_flag, entropy_coding_sync_enabled_flag,wpp_entry_point_offsets_present_flag,tile_entry_point_offsets_present_flag, offset_len_minus1,entry_point_offset_minus1, and/or num_entry_point_offsets syntaxelements.

The encoding apparatus encodes image/video information (S920). Theimage/video information may include the entry point related information.Further, the image/video information may include various pieces ofinformation according to an embodiment of the present document. Forexample, the image/video information may include information disclosedin at least one of Tables 1, 4, 5, 7, and/or 8 as described above.

The encoded image/video information may be output in the form of abitstream. The bitstream may be transferred to a decoding apparatusthrough a network or a storage medium.

Specifically, the entry point related information may include variouspieces of information based on the embodiments of the present document.

For example, the entry point related information may include offsetlength information and entry point offset information. For example, theoffset length information may be related to the number of bits of theentry point offset information. In other words, the offset lengthinformation may indicate/represent the number of bits of the entry pointoffset information.

For example, the offset length information may be expressed in the formof the offset_len_minus1 syntax element. For example, the value +1 ofthe offset_len_minus1 syntax element may specify the number of bits ofthe entry point offset information (e.g., entry_point_offset_minus1syntax element).

Also, the entry point offset information may represent the offsetbetween two entry points. For example, in this case, the entry pointoffset information may express the offset between the two entry pointsin byte units. For example, the entry point offset information may beexpressed in the form of the entry_point_offset_minus1 syntax element.For example, the value +1 of the entry_point_offset_minus1 syntaxelement may indicate to specify the offset in byte units.

Further, the entry point related information may include a WPP entrypoint offset present flag. For example, the WPP entry point offsetpresent flag may be related to whether the entry point offsets for theWPP are signaled. That is, the WPP entry point offset present flag mayindicate/represent whether the entry point offsets for the WPP aresignaled. For example, the entry point offset present flag may berepresented in the form of a wpp_entry_point_offsets_present_flag syntaxelement.

If the value of the WPP entry point offset present flag is 1, the offsetlength information and the entry point offset information may beconfigured/included in the slice header for the current slice.

Further, the entry point related information may include a no-picturepartition flag. For example, the no-picture partition flag may berelated to whether no-picture partitioning is applied to the currentpicture. That is, the no-picture partition flag may indicate/representwhether the no-picture partitioning is applied to the current picture.

For example, the no-picture partition flag may be represented in theform of the no_pic_partition_flag syntax element. For example, theno_pic_partition_flag syntax element may specify whether the no-picturepartitioning is applied to the current picture.

If the value of the no-picture partition flag is not 1, the offsetlength information and the entry point offset information may beconfigured/included in the slice header for the current slice.

If the value of the variable NumEntryPoints related to the number ofentry points being present in the current slice is larger than 0, theoffset length information and the entry point offset information may beincluded in the slice header to be signaled.

In this case, the offset length information and the entry point offsetinformation may be signaled without checking the value of the entrypoint offset present flag proposed in the related art.

The entry point related information may further include an entropycoding synchronization enabled flag, and the WPP entry point offsetpresent flag may be included in the PPS based on a case where the valueof the entropy coding synchronization enabled flag is 1.

Further, according to an embodiment of the present document, the entrypoint related information may further include a tile entry point offsetpresent flag. For example, the tile entry point offset present flag maybe related to whether the entry point offsets for the tile are signaled.That is, the tile entry point offset present flag may indicate/representwhether the entry point offsets for the tile are signaled.

For example, the tile entry point offset present flag may be representedin the form of the tile_entry_point_offsets_present_flag syntax element.For example, the tile_entry_point_offsets_present_flag syntax elementmay specify whether the entry point offsets for the tile are signaled.

In relation to this, if the value of the tile entry point offset presentflag is 1, the offset length information and the entry point offsetinformation may be configured/included in the slice header for thecurrent slice.

The entry point related information may include the no-picture partitionflag related to whether the no-picture partitioning is applied to thecurrent picture, and the tile entry point offset present flag may beincluded in the PPS based on a case where the value of the no-picturepartition flag is not 1.

FIGS. 11 and 12 illustrate an example of a video/image decoding methodand related components according to an embodiment(s) of the presentdocument. The method disclosed in FIG. 11 may be performed by thedecoding apparatus disclosed in FIG. 3 . Specifically, for example,S1100 and S1110 of FIG. 11 may be performed by the entropy decoder 310of the decoding apparatus, and S1120 of FIG. 9 may be performed by atleast one of the residual processor 320, the predictor 330, and/or theadder 340 of the decoding apparatus. The method disclosed in FIG. 11 mayinclude the embodiments described in the present document.

Referring to FIG. 11 , the decoding apparatus receives/obtainsimage/video information S1100. The decoding apparatus may receive/obtainthe image/video information through a bitstream. The image/videoinformation may include entry point related information. Also, theimage/video information may include various pieces of information basedon the embodiments of the present document. For example, the image/videoinformation may include the information disclosed in at least one ofTable 1, 4, 5, 7, and/or 8.

The decoding apparatus derives at least one entry point within a currentpicture based on the image/video information S1110. For example, thedecoding apparatus may derive whether WPP or tile technology is appliedto the current picture based on the entry point related informationincluded in the image/video information. When WPP is applied to thecurrent picture, the decoding apparatus may derive at least one entrypoint corresponding to at least one CTU row constituting the currentpicture. When tile technology is applied to the current picture, thedecoding apparatus may derive at least one entry point corresponding toat least one tile constituting the current picture.

The decoding apparatus performs decoding of the current slice/picturebased on the at least one entry point S1120. The decoding apparatus maydecode the slice/picture based on the at least one entry point. Thedecoding apparatus may decode the slice/picture in tile units and/or CTUrow units based on the at least one entry point. To this end, the intra,inter prediction method and residual processing method described abovemay be applied.

Here, the entry point related information may include various pieces ofinformation based on one embodiment of the present document.

For example, the entry point related information may include offsetlength information and entry point offset information. For example, theoffset length information may be related to the number of bits of theentry point offset information. In other words, the offset lengthinformation may indicate/represent the number of bits of the entry pointoffset information.

For example, the offset length information may be expressed in the formof the offset_len_minus1 syntax element. For example, the value +1 ofthe offset_len_minus1 syntax element may specify the number of bits ofthe entry point offset information (e.g., entry_point_offset_minus1syntax element).

Also, the entry point offset information may represent the offsetbetween two entry points. For example, in this case, the entry pointoffset information may express the offset between the two entry pointsin byte units. For example, the entry point offset information may beexpressed in the form of the entry_point_offset_minus1 syntax element.For example, the value +1 of the entry_point_offset_minus1 syntaxelement may indicate to specify the offset in byte units.

Further, the entry point related information may include the WPP entrypoint offset present flag. For example, the WPP entry point offsetpresent flag may be related to whether the entry point offsets for theWPP are signaled. That is, the WPP entry point offset present flag mayindicate/represent whether the entry point offsets for the WPP aresignaled. For example, the entry point offset present flag may berepresented in the form of the wpp_entry_point_offsets_present_flagsyntax element.

If the value of the WPP entry point offset present flag is 1, the offsetlength information and the entry point offset information may beconfigured/included in the slice header for the current slice.

Further, the entry point related information may include the no-picturepartition flag. For example, the no-picture partition flag may berelated to whether the no-picture partitioning is applied to the currentpicture. That is, the no-picture partition flag may indicate/representwhether the no-picture partitioning is applied to the current picture.

For example, the no-picture partition flag may be represented in theform of the no_pic_partition_flag syntax element. For example, theno_pic_partition_flag syntax element may specify whether the no-picturepartitioning is applied to the current picture.

If the value of the no-picture partition flag is not 1, the offsetlength information and the entry point offset information may beconfigured/included in the slice header for the current slice.

If the value of the variable NumEntryPoints related to the number ofentry points being present in the current slice is larger than 0, theoffset length information and the entry point offset information may beincluded in the slice header to be signaled.

In this case, the offset length information and the entry point offsetinformation may be signaled without checking the value of the entrypoint offset present flag proposed in the related art.

The entry point related information may further include an entropycoding synchronization enabled flag, and the WPP entry point offsetpresent flag may be included in the PPS based on a case where the valueof the entropy coding synchronization enabled flag is 1.

The WPP entry point offset present flag may be included in the PPS basedon a case where the current slice is composed of a plurality of CTUsincluded in a plurality of CTU rows.

Based on a case where the WPP entry point offset present flag isincluded in the PPS, each of the slices in the picture referring to thePPS may be able to be limited not to be composed of a plurality oftiles.

Further, according to an embodiment of the present document, the entrypoint related information may further include a tile entry point offsetpresent flag. For example, the tile entry point offset present flag maybe related to whether the entry point offsets for the tile are signaled.That is, the tile entry point offset present flag may indicate/representwhether the entry point offsets for the tile are signaled.

For example, the tile entry point offset present flag may be representedin the form of the tile_entry_point_offsets_present_flag syntax element.For example, the tile_entry_point_offsets_present_flag syntax elementmay specify whether the entry point offsets for the tile are signaled.

In relation to this, if the value of the tile entry point offset presentflag is 1, the offset length information and the entry point offsetinformation may be configured/included in the slice header for thecurrent slice.

The entry point related information may include the no-picture partitionflag related to whether the no-picture partitioning is applied to thecurrent picture, and the tile entry point offset present flag may beincluded in the PPS based on a case where the value of the no-picturepartition flag is not 1.

The tile entry point offset present flag may be included in the PPSbased on a case where the current slice is composed of a plurality oftiles.

Based on a case where at least one slice that is composed of a pluralityof tiles in the current picture is present, the WPP may be limited notto be applied to the current slice.

Although methods have been described on the basis of a flowchart inwhich steps or blocks are listed in sequence in the above-describedembodiments, the steps of the embodiments are not limited to a certainorder, and a certain step may be performed in a different step or in adifferent order or concurrently with respect to that described above.Further, it will be understood by those ordinary skilled in the art thatthe steps of the flowcharts are not exclusive, and another step may beincluded therein or one or more steps in the flowchart may be deletedwithout exerting an influence on the scope of the embodiments of thepresent document.

The aforementioned method according to the embodiments of the presentdocument may be in the form of software, and the encoding apparatusand/or decoding apparatus according to the present document may beincluded in a device for performing image processing, for example, a TV,a computer, a smart phone, a set-top box, a display device, or the like.

When the embodiments are implemented in software in the presentdocument, the aforementioned method may be implemented using a module(procedure, function, etc.) which performs the aforementioned function.The module may be stored in a memory and executed by a processor. Thememory may be disposed to the processor internally or externally andconnected to the processor using various well-known means. The processormay include application-specific integrated circuit (ASIC), otherchipsets, logic circuits, and/or data processors. The memory may includea read-only memory (ROM), a random access memory (RAM), a flash memory,a memory card, storage media and/or other storage devices. That is, theembodiments described herein may be implemented and performed on aprocessor, a microprocessor, a controller, or a chip. For example, thefunctional units shown in each drawing may be implemented and performedon a computer, a processor, a microprocessor, a controller, or a chip.In this case, information for implementation (e.g., information oninstructions) or an algorithm may be stored in a digital storage medium.

Further, the decoding apparatus and the encoding apparatus to which theembodiment(s) of the present document is applied may be included in amultimedia broadcasting transceiver, a mobile communication terminal, ahome cinema video device, a digital cinema video device, a surveillancecamera, a video chat device, and a real time communication device suchas video communication, a mobile streaming device, a storage medium,camcorder, a video on demand (VoD) service provider, an over the topvideo (OTT) device, an internet streaming service provider, a 3D videodevice, a virtual reality (VR) device, an augment reality (AR) device,an image telephone video device, a vehicle terminal (e.g., a vehicle(including an autonomous vehicle) terminal, an airplane terminal, a shipterminal, etc.) and a medical video device, and the like, and may beused to process a video signal or a data signal. For example, the OTTvideo device may include a game console, a Blu-ray player, anInternet-connected TV, a home theater system, a smartphone, a tablet PC,a digital video recorder (DVR), and the like.

Further, the processing method to which the embodiment(s) of the presentdocument is applied may be produced in the form of a program beingexecuted by a computer and may be stored in a computer-readablerecording medium. Multimedia data having a data structure according tothe embodiment(s) of the present document may also be stored in thecomputer-readable recording medium. The computer readable recordingmedium includes all kinds of storage devices and distributed storagedevices in which computer readable data is stored. The computer-readablerecording medium may be, for example, a Blu-ray disc (BD), a universalserial bus (USB), a ROM, a PROM, an EPROM, an EEPROM, a RAM, a CD-ROM, amagnetic tape, a floppy disk, and an optical data storage device. Thecomputer-readable recording medium also includes media embodied in theform of a carrier wave (e.g., transmission over the Internet). Further,a bitstream generated by the encoding method may be stored in thecomputer-readable recording medium or transmitted through a wired orwireless communication network.

In addition, the embodiment(s) of the present document may be embodiedas a computer program product based on a program code, and the programcode may be executed on a computer by the embodiment(s) of the presentdocument. The program code may be stored on a computer-readable carrier.

FIG. 13 represents an example of a content streaming system to which theembodiments described in the present document may be applied.

Referring to FIG. 13 , the content streaming system to which theembodiments of the present document are applied may generally include anencoding server, a streaming server, a web server, a media storage, auser device, and a multimedia input device.

The encoding server functions to compress to digital data the contentsinput from the multimedia input devices, such as the smart phone, thecamera, the camcorder and the like, to generate a bitstream, and totransmit it to the streaming server. As another example, in a case wherethe multimedia input device, such as, the smart phone, the camera, thecamcorder or the like, directly generates a bitstream, the encodingserver may be omitted.

The bitstream may be generated by an encoding method or a bitstreamgeneration method to which the embodiments of the present document areapplied. And the streaming server may temporarily store the bitstream ina process of transmitting or receiving the bitstream.

The streaming server transmits multimedia data to the user equipment onthe basis of a user's request through the web server, which functions asan instrument that informs a user of what service there is. When theuser requests a service which the user wants, the web server transfersthe request to the streaming server, and the streaming server transmitsmultimedia data to the user. In this regard, the content streamingsystem may include a separate control server, and in this case, thecontrol server functions to control commands/responses betweenrespective equipment in the content streaming system.

The streaming server may receive contents from the media storage and/orthe encoding server. For example, in a case the contents are receivedfrom the encoding server, the contents may be received in real time. Inthis case, the streaming server may store the bitstream for apredetermined period of time to provide the streaming service smoothly.

For example, the user equipment may include a mobile phone, a smartphone, a laptop computer, a digital broadcasting terminal, a personaldigital assistant (PDA), a portable multimedia player (PMP), anavigation, a slate PC, a tablet PC, an ultrabook, a wearable device(e.g., a watch-type terminal (smart watch), a glass-type terminal (smartglass), a head mounted display (HMD)), a digital TV, a desktop computer,a digital signage or the like.

Each of servers in the content streaming system may be operated as adistributed server, and in this case, data received by each server maybe processed in distributed manner. The claims described herein may becombined in various ways. For example, the technical features of themethod claims of the present specification may be combined andimplemented as an apparatus, and the technical features of the apparatusclaims of the present specification may be combined and implemented as amethod. In addition, the technical features of the method claims of thepresent specification and the technical features of the apparatus claimsmay be combined to be implemented as an apparatus, and the technicalfeatures of the method claims and the technical features of theapparatus claims of the present specification may be combined andimplemented as a method.

What is claimed is:
 1. An image decoding method performed by a decodingapparatus, the method comprising: obtaining image information through abitstream, wherein the image information includes entry point relatedinformation; deriving at least one entry point in a current picturebased on the entry point related information; and decoding the currentpicture based on the at least one entry point, wherein the entry pointrelated information includes offset length information and entry pointoffset information, and the offset length information is related to anumber of bits of the entry point offset information, wherein based onthe offset length information and the entry point offset information,the at least one entry point is derived, wherein the entry point relatedinformation includes a wavefront parallel processing (WPP) entry pointoffset present flag related to whether entry point offsets for WPP aresignaled, and wherein based on a case where a value of the WPP entrypoint offset present flag is 1, the offset length information and theentry point offset information are included in a slice header for acurrent slice.
 2. The method of claim 1, wherein the entry point relatedinformation includes an entropy coding synchronization enabled flag, andthe WPP entry point offset present flag is included in a pictureparameter set (PPS) based on a case where a value of the entropy codingsynchronization enabled flag is
 1. 3. The method of claim 2, wherein theWPP entry point offset present flag is included in the PPS based on acase where the current slice is composed of a plurality of CTUs includedin a plurality of CTU rows.
 4. The method of claim 2, wherein based on acase where the WPP entry point offset present flag is included in thePPS, each of slices in a picture referencing the PPS is restricted so asnot to be composed of a plurality of tiles.
 5. The method of claim 1,wherein the entry point related information includes a tile entry pointoffset present flag related to whether entry point offsets for tile aresignaled, and wherein based on a case where a value of the tile entrypoint offset present flag is 1, the offset length information and theentry point offset information are included in the slice header for thecurrent slice.
 6. The method of claim 5, wherein the entry point relatedinformation includes a no-picture partition flag related to whetherno-picture partitioning is applied to the current picture, and whereinthe tile entry point offset present flag is included in a pictureparameter set (PPS) based on a case where a value of the no-picturepartition flag is not
 1. 7. The method of claim 6, wherein the tileentry point offset present flag is included in the PPS based on a casewhere the current slice is composed of a plurality of tiles.
 8. Themethod of claim 1, wherein the entry point related information includesa no-picture partition flag related to whether no-picture partitioningis applied to the current picture, and wherein based on a case where avalue of the no-picture partition flag is not 1, the offset lengthinformation and the entry point offset information are included in theslice header for the current slice.
 9. The method of claim 1, based on acase where at least one slice consisting of a plurality of tiles in thecurrent picture is present, the WPP is not applied to the current slice.10. An image encoding method performed by an encoding device, the methodcomprising: deriving at least one entry point in a current picture;generating entry point related information based on the at least oneentry point; and encoding image information including the entry pointrelated information, wherein the entry point related informationincludes offset length information and entry point offset information,and the offset length information is related to a number of bits of theentry point offset information, wherein the entry point relatedinformation includes a wavefront parallel processing (WPP) entry pointoffset present flag related to whether entry point offsets for WPP aresignaled, and wherein based on a case where a value of the WPP entrypoint offset present flag is 1, the offset length information and theentry point offset information are included in a slice header for acurrent slice.
 11. The method of claim 10, wherein the entry pointrelated information includes an entropy coding synchronization enabledflag, and the WPP entry point offset present flag is included in apicture parameter set (PPS) based on a case where a value of the entropycoding synchronization enabled flag is
 1. 12. The method of claim 10,wherein the entry point related information includes an tile entry pointoffset present flag related to whether entry point offsets for tile aresignaled, and wherein based on a case where a value of the tile entrypoint offset present flag is 1, the offset length information and theentry point offset information are included in the slice header for thecurrent slice.
 13. The method of claim 12, wherein the entry pointrelated information includes a no-picture partition flag related towhether no-picture partitioning is applied to the current picture, andwherein the tile entry point offset present flag is included in apicture parameter set (PPS) based on a case where a value of theno-picture partition flag is not
 1. 14. The method of claim 10, whereinthe entry point related information includes a no-picture partition flagrelated to whether no-picture partitioning is applied to the currentpicture, and wherein based on a case where a value of the no-picturepartition flag is not 1, the offset length information and the entrypoint offset information are included in the slice header for thecurrent slice.
 15. A computer-readable digital storage medium storingencoded information causing a decoding device to perform an imagedecoding method, the image decoding method comprising: obtaining imageinformation through the encoded information, wherein the imageinformation includes entry point related information; deriving at leastone entry point in a current picture based on the entry point relatedinformation; and decoding the current picture based on the at least oneentry point, wherein the entry point related information includes offsetlength information and entry point offset information, and the offsetlength information is related to a number of bits of the entry pointoffset information, wherein based on the offset length information andthe entry point offset information, the at least one entry point isderived, wherein the entry point related information includes awavefront parallel processing (WPP) entry point offset present flagrelated to whether entry point offsets for WPP are signaled, and whereinbased on a case where a value of the WPP entry point offset present flagis 1, the offset length information and the entry point offsetinformation are included in a slice header for a current slice.